1. Field of the Invention
This invention relates to a binocular microscope having a range of variable magnifications and more particularly to a binocular microscope utilized in micro-surgery which accommodates the natural eye-hand coordination of the surgeon.
2. Background Information
Microscopes are used by surgeons for operating in situations where viewing fine detail is critical. Operating on a patient's brain is but one example of such a situation. In a typical operating setting, the patient is prone on the operating table and the microscope is positioned above the area being operated on. This "area" is hereafter sometimes referred to as the work area. Care is taken to see that the work area is accessible so as to enable the surgeon to see the work area and also to enable the surgeon to manipulate the surgical instruments within the work area.
Microscopes in use prior to this invention provided the desirable features of a binocular type eyepiece through which the surgeon views the area; zoom lens capabilities to allow the surgeon to increase or decrease the magnification of the area; a second binocular type eyepiece for viewing by an assistant; and a viewing lens for taking photographs or video recordings.
To provide an unobstructed view of the area being worked on, the microscope is placed above and directed vertically onto the work area. The lenses, including the zoom system, is encased in the vertically oriented housing of the microscope. The surgeon, however, cannot conveniently look straight down through the microscope due to its length which would position the surgeon too far from the work area. Thus, the eyepiece is placed at an angle to the housing of the microscope so that viewing the work area is possible with a more natural positioning of the head. This angular positioning is accomplished with mirrors and/or prisms and is well known to the art.
There are many different kinds of operating microscopes but, from what is known, they all have a common problem. The projected line of sight through the eyepiece is not directly aimed at the work area. This is due to the fact that the eyepiece is at an angle with respect to the housing of the microscope. The eyepiece, in other words, directs the surgeon's eyes away from, rather than coincident with the work area. This is unnatural in that the surgeon is looking in a direction toward one area while his hands are required to work in another.